1. Field of the Invention
The disclosed and claimed concept relates to concrete forms and, more specifically, to a telescopic concrete form.
2. Background Information
A concrete form is a frame used to support wet concrete and define the shape of the resulting concrete slab. Traditionally, the concrete form was a wooden board, such as, but not limited to, a 2″×6″, a 2″×8″, or a 2″×10″. The wooden board could have a release coating applied thereto. Such boards would be positioned so as to enclose the vertical sides of the resulting concrete slab. The wet concrete would be poured within the forms, leveled off by screeding the concrete (i.e. moving a straight edge, usually another board, back and forth over the upper surface of the forms thereby leveling off the concrete), and allowed to dry. The forms were then removed leaving the dry concrete slab. One disadvantage of using wooden boards was that the boards would degrade over time. Another disadvantage was that boards are, typically, cut in standard lengths. Thus, if the form needed to be longer than a standard board, two or more boards would be coupled together until the desired length was obtained. Further, if the form required a key, as discussed below, fabrication of the key required extra wood and time to assemble.
One solution to these disadvantages was to provide a telescoping metal form such as the device disclosed in U.S. Pat. No. 5,655,336. This patent discloses two C-shaped metal members disposed in a spaced, telescoping relationship. The members included a support device disposed on the open side of the C-shaped members. This device has disadvantages as well. First, the upper surface of the inner telescoping member was disposed in a plane parallel to, but below, the plane of the outer member upper surface. The degree to which the surfaces are uneven was exacerbated by spacing ridges on the inner surface of the outer member. These factors created a non-planar upper surface to the form assembly. The non-planar upper surface prevented screeding or caused the screeding to produce a non-planar surface on the concrete. Similarly, the vertical forming surface of the device was uneven as well resulting in a vertical face on the slab that included two or more planar surfaces that were not aligned. Such an uneven vertical face is not desirable on an outer vertical face of a concrete slab.
There is, therefore, a need for an improved concrete form that provides a substantially planar upper surface. There is a further need for an improved concrete form that provides a substantially planar vertical face.